Laminate constructs for micro-fluid ejection devices

ABSTRACT

A micro-fluid ejection head has an ejection chip to expel fluid. It connects to a laminate construct. The construct has vertically configured wiring layers interspersed with non-conductive layers, such as carbon fiber layers. An upper of the wiring layers electrically connects to the ejection chip. The upper layer may also support a planar undersurface of the chip directly on a surface or in a recessed pocket. The two can connect with a die bond, such as one having silica or boron nitride. Fluid connections exist between ink feed slots of the chip and the laminate construct. A silicon tile or other material may also fluidly interconnect with the two. A plastic manifold optionally supports the laminate construct and may fluidly connect to it. The wiring layers of the laminate contemplate ground, power, and various bond pads. Other construct layers contemplate prepreg or core FR4 layers.

FIELD OF THE INVENTION

The present invention relates to micro-fluid ejection devices, such asprinters, copiers, graphics plotters, all-in-ones, etc. Moreparticularly, it relates to laminate constructs serving multiplefunctions that minimize the number of components, processing steps andsize required for ejection heads, e.g., inkjet printheads.

BACKGROUND OF THE INVENTION

The art of printing images with micro-fluid technology is relativelywell known. A conventional permanent or semi-permanent ejection head hasaccess to a local or remote supply of fluid. The fluid ejects from anejection zone of the head to a print media in a pattern corresponding topixels of images being printed. Over time, the heads and fluid dropshave become smaller.

As part of recent trends, manufacturers increasingly have placed theirinkjet ejection chips on ceramic substrates. Ceramics are relativelyhigh modulus materials offering low coefficients of thermal expansion(CTEs). They are known to minimize chip bow in comparison to diesmounted directly on molded plastic substrates, especially when usingepoxy die bond materials having elevated cure temperatures (typically inthe range 110.degree.-150.degree. C.). In multi-chip, wide-swathejection heads, ceramics provide benefit during thermal processing stepssubsequent to preliminary die-to-substrate attachment, such as bymaintaining a die's relative position during encapsulation cure, printedcircuit board (PCB) attachment cure, wire bonding, etc.

Notwithstanding these advantages, ceramics have known drawbacks. One,manufacturers need to set dimensional tolerances fairly high sinceceramics shrink during firing processes. As it stands, placementaccuracies are compromised for fluid (ink) vias and bridges and theirlocations relative to each other and to components residing nearterminal edges. Dry-pressed ceramics have typical tolerances of +/−200.mu.m while those from more expensive ceramic injection molding (CIM)processes are smaller. Two, ceramics based in alumina have limitedthermal conductivity and most do not incorporate any electricalfunctionality unless founded in tape cast varieties, such as HTCC(94-98% alumina) and LTCC (.about.40% glass in alumina). Tape castvarieties, however, are relatively expensive to fabricate and each comeswith challenges in selecting compatibility relative to other materials.For instance, one grade of LTCC material examined by the inventorscaused ink to flocculate, while selected HTCC materials requiredcorrespondingly low-conductivity trace (metal) materials, such astungsten, when utilized in high-temperature firing environments. Three,there exists a practical limitation in the sizes of substrates that canbe fabricated due to corresponding limitations in the sizes of modernpresses. Naturally, this creates problems for manufacturers seeking toincrease dimensions in printing swaths and chip arrays.

With reference to FIG. 1A, an ejection head 10 is formed with a PCB 12and flexible cable 14. The PCB embodies a four wiring layer board andmounts on a ceramic substrate 16. The board provides electricalconnections to ejection chips that reside in cutout “pockets” 18. Thedesign adds electrical functionality over earlier, single layer TABcircuit, flexible circuit, solutions due to its presence of ground andpower planes in the four wiring layers and an ability to combine andcross signal lines. When the PCB is configured with a material set ofFR4 (the international grade designation for “Flame Retardant” (FR)fiberglass reinforced epoxy laminates), the design has further advantagein its compatibility with certain ink sets. However, there remainslimits and unresolved process challenges as will be seen.

For example, a depth of the pocket 18 cannot be thicker than the chip itcarries or material of the board will encroach into a paper gap distanceof the ejection device. Also, the thickness of the PCB is best situatedto remain .about. 100 um lower than the chip surface to help minimizewire bond loop heights above the head's nozzle plate. However, a chipthickness of 450 .mu.m limits the thickness of the board to no more than350 .mu.m (.about. 14 mils) (e.g., 450 .mu.m-100 .mu.m). In a four (4)wiring layer board (e.g., wire bond pads on top, internal power andground planes, routing interconnections and solder pads for flexiblecable interconnect on bottom), this keeps the thickness of the boardcritically close to a minimum thickness of a board that can be made. Italso limits the space to add a protective FR4 layer to the bottom of theboard, such as over trace areas so that the only exposed metal on thebottom is for flexible cable attachment pads. By allowing a thicker die,on the other hand, the board thickness can increase but at an adversecost to the substrate of poorer thermal dissipation.

In other setbacks, current corrosion protection for wiring traces isprovided by an adhesive that attaches the board 12 to the ceramicsubstrate 16. However, since the boards are thin and flexible, they tendto warp after fabrication. This not only presents challenges forattaching the board to the ceramic, but compromises corrosion protectionfor the traces. Still other problems associated with board-to-ceramicattachment include: 1) squeezing epoxy excesses into the chip pocketcausing, thereby interfering with later die mounting or contributing tovolume variability in the pocket and making encapsulation heightsunpredictable; or 2) creating interfacial voids that allow ink to accessthe delicate wiring traces on the bottom of the board.

Alignment or registration between the board and ceramic has alsoresulted in manufacturing concerns. One, the board warping makes itdifficult to properly register components. Two, routing tolerances onthe board provide little room to adjust components. Three, vision systempick-and-place fixtures require holding one piece steady while attachingthe other with adhesive. As ejection heads move beyond single- ordouble-chip heads to larger arrays, the weight of now larger ceramicsbecomes problematic for smaller pick-and-place tools. Then, once placed,the board and ceramic must be fast-tacked during a preliminary cure stepfor transfer to a more permanent cure. However, UV curing lamps andother gluing fixtures are difficult to incorporate into standardtooling. Also, selections of compatible tack-and-hold and permanentbonding adhesives need be contemplated when making tooling selections.While none of the problems are individually insurmountable, a needexists in the art to simplify the process.

As part of solutions to the foregoing problems, third parties haveintroduced various epoxy based PCB's. They are thought to provideelectrical functionality in low cost manufacturing items. They alsosidestep many of the ceramic limitations noted above. Some have evenbeen used as substrates for micro-fluidic applications. For example,U.S. Pat. No. 6,821,819 proposes using a PCB as a substrate and fluidicmanifold for a microfluidic device chip like a biosensor, chemicalsensor, or other electro microfluidic device. In U.S. Pat. No.7,347,533, a piezoelectric inkjet printhead is constructed from a PCBmaterial with driver chips affixed to the board. Neither of these,however, concern themselves with the challenges associated withprecision methods needed to attach silicon inkjet chips to PCBmaterials. Rather, they relate to using conventional PCB material sets,which are insufficient for modern concerns.

When ejection head designs use a thermally cured adhesive, chip bow isaffected by the modulus, CTE and thickness of the die, substrate, andadhesive together with the glass transition temperatures of thesematerials and the delta T between cure temperature and ambient. Usinghigh Tg substrates with low CTEs are the better product for less stresson the die. Typical FR4 PCB materials, however, have CTEs of .about.16-20 ppm/.degree. C. and represent poor substrates for attachment tosilicon chips having CTEs of 2-4 ppm/.degree. C. While ceramic materialswith CTEs of 6-8 ppm/.degree. C. are a better match, they suffer theproblems identified above. Also, standard FR4 based circuit boards maynot provide enough rigidity/stiffness for micro-fluid applications. Inturn, mounting a board assembly to a printhead body can inducesignificant stresses that may translate into deformation where the dieinterfaces with the FR4 substrate. Further, thermal conductivities ofstandard FR4 materials are very low when compared to ceramic (0.3-0.4W/mK vs. .about. 25 W/mK), and this could prove challenging fordissipating heat generated during printing.

In other modern designs, page-wide ejection heads are contemplatedhaving arrays of very narrow ejection chips (<2 mm). Each chip includesmultiple minute through holes feeding ink to each firing chamber insteadof a single large via feeding ink. In comparison to larger conventionalchips, the design enjoys more efficient use of silicon since large “realestate” need not be consumed by structurally supporting the large via orproviding fluidic channels to each firing chamber. Instead, fluidicchannels are confined to manifolds above and/or below the layers ofpatterned silicon on the chip. For one of many competing proposals onhow best to construct the manifold, see, e.g., U.S. patent applicationSer. No. 12/624,078, filed Nov. 23, 2009, incorporated herein byreference.

With reference to FIG. 4, an initial concept is seen for establishingfluidic and electrical interconnections in the '078 application. Itincludes an ejection chip and fluid manifold (silicon) 20. The ejectionchip and manifold may be fabricated in a single piece of silicon or theymay be separate pieces of silicon bonded in a laminar construct. Thefluid manifold portion of this construct consists of fluid channelsrunning the long axis of the chip, typically one per color of ink or perrow of nozzles. The chip wire bonds 22 electrically to a printed circuitboard 24. The board connects to a flexible circuit 26 which connects toprinter electronics (not shown). Fluidically, the manifold communicateswith a tile 28. The tile is silicon-based (absent thin film patternedlayers) and has a thickness of about 400-600 .mu.m. Its manufacturingand interface to the manifold is more thoroughly described in U.S.patent application Ser. No. 12/568,739, filed Sep. 29, 2009, and such isalso incorporated herein by reference. In general, however, the tile hasports on its top that fluidly mate with slots on the bottom of themanifold. It also has lateral channels at its bottom (orthogonal to thelong axis of the ejection chip) that fluidly connect in stagger tothrough holes in a rigid substrate 30 (e.g. ceramic base). Thesubstrate, in turn, provides both mechanical support and rigidity to theoverall assembly. Ultimately, the goal of the fluidic arrangement is tofan-out the fluidic channels downward from the chip and condense theminto a single port connection for each color. However, the design needsa “large enough” separation/seal distance so that a fluidic feed tube orplastic housing can be easily connected with a compliant rubber gasketor a needle-dispensed liquid adhesive. For adhesives typically used inmicro-fluidic connections, the minimum achievable seal distances withneedle dispense, without having either leaks, and crosstalk, betweencolors or excessive adhesive “squeeze-out” causing blockages in fluidicpaths has been established as approximately 500 .mu.m of “land area”between adjacent fluidic features. Unfortunately, the printed circuitboard 24 and ceramic base substrate 30 cause the design to encountermuch of the same problems earlier described.

Accordingly, a further need exists in the art to accommodate pluralitiesof components in ejection heads having diverse functionality. Additionalbenefits and alternatives are also sought when devising solutions.

SUMMARY OF THE INVENTION

The above-mentioned and other problems become solved with laminateconstructs for micro-fluid ejection heads. Broadly, the concept proposesto combine the mechanical substrate function of a ceramic base with theelectrical function of a PCB. It eliminates the expense of a ceramiccomponent and minimizes challenges to attaching PCBs. It also avoidsthermal curing stresses on the PCB-flex joint/seal or all-flex wiringassembly.

A micro-fluid ejection head has an ejection chip to expel fluid toward aprint media during use. It connects to a laminate construct. Theconstruct has vertically configured wiring layers interspersed withnon-conductive layers, such as carbon fiber layers. An upper of thewiring layers electrically connects to the ejection chip. The upperlayer may also support a planar undersurface of the chip directly on asurface or in a recessed pocket. The two can connect with a die bond,such as one having silica or boron nitride. Fluid connections existbetween ink feed slots of the chip and laminate construct. A silicontile or other material may also fluidly interconnect with the two. Aplastic manifold optionally supports the laminate construct and mayfluidly connect to it. The wiring layers of the laminate constructrepresentatively include ground, power, and bond pads. Other constructlayers representatively include prepreg or core FR4 layers.

In any embodiment, the ejection head is configured without sacrificingCTE match, stiffness/rigidity, or thermal conductivity. It does so bytaking advantage of recent developments in carbon fiber PCB laminatetechnology to address some key drawbacks of traditional PCB/FR4 materialsets as they apply to inkjet printhead construction. Due to largelaminate panel processing in common usage at board manufacturers, a PCBapproach is more easily extensible to larger form factors (and page-wideejection heads) than is a ceramic approach limited to those shapes/sizesthat can be easily molded using dry pressing or ceramic injectionmolding. The use of a Stablcor™ carbon fiber laminate PCB is but onerepresentative embodiment of a laminate construct that is useful inreplacing the functionality of a ceramic substrate and PCB electricalinterconnect component.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings incorporated in and forming a part of thespecification, illustrate several aspects of the present invention, andtogether with the description serve to explain the principles of theinvention. In the drawings:

FIG. 1A is a diagrammatic view in accordance with the prior art of a PCBand ceramic base attachment for an ejection head;

FIG. 1B is a diagrammatic view in accordance with the present inventionof a laminate construct for a micro-fluid ejection head;

FIG. 2 is a diagrammatic view in accordance with the present inventionof a more detailed laminate construct;

FIGS. 3A and 3B are diagrammatic views in accordance with the presentinvention of an alternate design for a laminate construct includingattached fluid flow features for an ejection head;

FIG. 4 is a diagrammatic view in accordance with the prior art of analternate design of a PCB and ceramic base attachment for an ejectionhead; and

FIGS. 5-9 are diagrammatic views in accordance with the presentinvention of other alternate laminate construct designs for micro-fluidejection heads.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

In the following detailed description, reference is made to theaccompanying drawings where like numerals represent like details. Theembodiments are described in sufficient detail to enable those skilledin the art to practice the invention. It is to be understood that otherembodiments may be utilized and that process, electrical, and mechanicalchanges, etc., may be made without departing from the scope of theinvention. The following detailed description, therefore, is not to betaken in a limiting sense and the scope of the invention is defined onlyby the appended claims and their equivalents. In accordance with thepresent invention, methods and apparatus describe a laminate constructfor an ejection head useful in micro-fluid ejection devices.

With reference to FIG. 1B, a representative ejection head 40 includes aflexible cable 42 and a laminate construct 44. The laminate constructsupports one or more ejection chips 46-1, 46-2 that eject fluid toward aprint media during use. The laminate construct replaces the PCB andceramic substrate components of FIG. 1B, and their functionality.Ultimately, it provides a rigid, lightweight, CTE matched, thermallyconductive substrate with electrical wiring/interconnect. Robustcorrosion protection is also afforded by having eliminated the adhesiveinterface between the PCB and ceramic and its associated traceprotection requirements on the adhesive at this same location. Inprocess, it avoids the challenging assembly step and thermal cure cycleof PCB-to-ceramic attachment. Further, thermal dissipation is improvedversus plastic or ceramic bases, as will be seen.

In a more detailed design in FIG. 2, the laminate construct embodies aplurality of vertically stacked wiring layers (L1, L2, L3, L4)interspersed with non-conductive layers (prepreg, FR4 core andcarbon-fiber based layers 50). An upper layer L1 of the wiring layerselectrically connects to the ejection chip 46, such as by wire bonding51. Each ejection chip 46 and the laminate construct have fluid flowfeatures, e.g., ink feed slots 53, 55, in fluid communication with oneanother to convey fluid from a reservoir (not shown) through thelaminate construct and into the ejection chip during use. Also, theupper layer defines a substantially planar surface 57 for supporting asubstantially planar undersurface 59 of the ejection chip.Alternatively, the upper layer may define a recess or pocket forsupporting the chip (described in more detail below, FIG. 7). Witheither, a die bonding material 61 is further useful to secure movementbetween the two structures. Optional copper (Cu) layers in the construct44 may further enhance thermal conductivity of the design and/or addstrength. Because of its conductivity, one or more of the Cu layers maydefine an electrical plane, such as ground.

A particularly useful carbon fiber layer 50 for use in the laminateconstruct is a Stablcor.RTM. brand composite laminate board.Alternatively, an entirety of the laminate construct 44 can typify oneor more Stablcor boards. In the example given, two layers of Stablcormaterial (not electrically functional) are included in a laminatestructure with the four wiring layers. The two Stablcor layers areseparated from one another and are balanced around the neutral axis ofthe board to impart stiffness.

A thickness of the laminate construct varies, but is seen here in arange of about 2-3 mm, especially 2.4 mm. Its inner layers of prepregFR4 are relatively thinner than its outer layers of prepreg FR4. Theinner layer is about 5 mils, while the outer is about 9 mils. The coreFR4 layer, on the other hand, is about 50 mils and each of thecarbon-fiber based layers typify about 9-18 mils. Of course, other sizesare possible.

The fluidic features in the construct (ink slots 55) are fabricated witha variety of techniques, but representative processes include standardPCB fabrication techniques, such as routing, drilling, punching, orother cutting process (e.g., laser, waterjet, etc.). Similarly, the inkslots 53 in the chip 61 are traditionally formed, such as by etching,grit blasting, or the like. The features are shown as slots in both thechip and construct, but could further embody fluid ports, holes, etc.,to enable connection to manifolds, described below, and those seen inthe earlier patent applications incorporated by reference. When embodiedas shown, drill sizes as small as 6 mils are commonly available fortooling which lends itself to location tolerances of +/−2 mils over apanel as large as 18″.times. 24″. Milled slots are also possible, butwith slightly larger tolerances being on the order of about +/−3 mils.Either compares favorably to dry-pressed ceramic components havingtypical tolerances of about +/−8 mils. The Cu layers of the constructcan be imaged and patterned as needed. This allows copper to be pulledback from nearby cut edges that reside closely to ink flows, such asnearby position 63.

In other embodiments, narrow flow features 65 can be fabricated on thebackside of the construct, instead of slots, by way of laser cutting orpunched-film (such as polyimide (PI) film 67) and then attached with anadhesive (such as an epoxy) as represented in FIGS. 3A and 3B. In stillanother option, a two step routing process contemplates first millingslots partway through the laminate construct and then formingports/narrow flow features through the remainder of the board.Alternatively still, a narrow flow feature including a taper/funnelprofile to avoid bubble entrapment points could be molded in a plasticcomponent and then attached to the back of the laminate construct withan adhesive. Various plastic embodiments will be seen below.

In any design, the carbon-fiber laminate boards developed by Stablcorhave been recently demonstrated to allow CTEs to be tailored over therange of 3-12 ppm/.degree. C. As is known, the carbon fiber compositelayers consist generally of a carbon fiber weave in an epoxy matrix. Thelayer is electrically and thermally conductive and can be used as aground (or power) plane and/or for thermal dissipation. A maindifference in comparison to a standard FR4 core is that the FR4's glassfibers are replaced with carbon fibers. The weave pattern is alsobalanced with an equal number of fibers in the X and Y axes. In thisway, electrical and thermal conduction properties are anisotropic withhighest conduction rates occurring along the X and Y axes.

As is reported by Stablcor at its website www.stablcor.com, forinstance, there are several grades of carbon fiber laminate cores fromwhich to choose. In one embodiment, ST10 and ST325 grades are availablewith the CTE benefits noted above. Their thermal conductivities arereported as 8 and 325 W/mK, respectively. When including coppercladding, their conductivities are 75 and 175 W/mK, respectively. Incomparison to a substrate of ceramic at a thermal conductivity of.about. 25 W/mK, the carbon fiber layers are favorable.

Similarly, the tensile moduli of Stablcor layers are favorable over PCBsas noted three to seven times higher than that of standard FR4/E-glasslayers. When multiple such carbon-fiber layers are built into a singlelaminate construct, an added advantage is that of dramatically increasedflexural modulus. As touted, Stablcor claims an increase of more thantwo times the flexural modulus of a standard FR4 PCB depending on howmany Stablcor layers are used, their thickness, and relative location inthe “stack-up.” Because their densities are similar to that oftraditional PCB materials and much lower than ceramic materials, theproposed weight of the final assembly in FIG. 1B, for example, is muchlighter than that of the prior art design in FIG. 1A. This is of furtherimportance in a micro-fluid ejection device where the ejection headsscan back and forth over a media during use since it reducesmomentum/inertia of the head carriage.

Lastly, the laminate constructs including or typifying an entirety ofStablcor layers are at lower risk for brittle fracture in comparison toceramics. In turn, better mechanical damping is afforded ejection chips46, thereby lower the risk of damage during shipping and handling.

EXAMPLE

As an initial proof of concept, the inventors have mounted dies onseveral Stablcor layers of the above construction using the same diebond material, dispense, and pick-and-place processes used onconventional ceramic substrate designs. Thickness were somewhatarbitrarily set and design and process conditions were not optimized forplanarity in the chip pocket area. Result: Y-axis chip bows wereobserved at less than 5 .mu.m over a ½ inch chip length. While such isnot as good as the 1-2 .mu.m achieved on ceramic substrates, it isconsiderably better than the 15-16 .mu.m achieved on other designs (notshown). It is believed that with the optimization of planarity betweenthe chip and laminate construct, results will be further improved.

With reference to FIGS. 5-9, the laminate construct 44 is further usefulin overcoming the disadvantages of the design in FIG. 4 (prior art). Inall such embodiments, the laminate constructs are intended to providefluidic and electrical interconnections to very narrow ejection chipsfor use in devices such as wide swath printheads. Also, the ejectionheads can be defined as either a single monolithic substrate or in amodular construction where construction contemplates many suchmonolithic substrates.

As seen in FIG. 5, a first embodiment utilizes a laminate construct 44to replace the combined functionality of the prior art's PCB (24, FIG.4) and ceramic substrate base (30, FIG. 4). It also includes an ejectionchip and fluid manifold (silicon) 20, as before, and the chip connectselectrically to the laminate construct, such as by wire bond 22. As inthe initial concept, there remains a tile layer (silicon) 28 interposedbetween the manifold/chip 20 and the laminate construct and fluidconnections “fan-out” from the manifold/chip 20, to the tile, to thelaminate construct. Although not shown here, the ports on the back ofthe tile are mated to the through-hole ports on the laminate construct.Small ports (through holes) are fabricated in the construct as before,such as by drilling or laser cutting. To make the actual electricalconnection from the top surface of the ejection chip down to the upperlayer of the laminate construct, the construct has a footprintprotruding slightly at position 45 beyond a footprint of the tile.

With reference to FIG. 6, an alternate embodiment envisions the laminateconstruct 44 replacing not only the combined functionality of the priorart's PCB (24, FIG. 4) and ceramic substrate base (30, FIG. 4), but alsothe tile (28, FIGS. 4 and 5). A plastic manifold 70 is also added insupport of the laminate construct 44 to reveal additional structuresavailable with an ejection head. In detail of the laminate constructshown to the right, the construct has small ports for placement in fluidcommunication with the corresponding ports on the bottom side of themanifold/chip 20. To the extent the channel width on the bottom of themanifold/chip 20 is sufficiently large, then it is possible that thefluidic path in the laminate construct alternatively embodies throughholes. For fluidic reasons, the design may dictate keeping an aspectratio of no more than 2:1 such that a 200 .mu.m channel width wouldresult in a 400 .mu.m laminate thickness with through holes. On theother hand, if the channel widths are smaller (for example, one currentembodiment has 80 .mu.m channels), then the laminate will be required toperform some of the fan-out/fluidic path expansion from a top of thelaminate to the bottom as it is not likely possible to create a fourwiring layer laminate that is wholly less than 160 .mu.m thick. Asdepicted in the three layers shown on the right side of bracket for thelaminate construct 44, the port layer 75, lateral channels 77, andlarger ports 79 (fabricated in FIG. 4 in its tile and ceramic layers)may be punched or laser cut in the non-conductive layers (FIG. 2) of thelaminate construct prior to a lamination step of creating the entiretyof the multiple layers of the laminate construct 44.

Actual instances of crafting the flow features in the laminate constructinclude instances of the following: 1) etching lateral fluidic channelsin metal layers followed by plating; 2) stacking/joining multiple suchlayers; and 3) adhesively attaching the entirety of the layers (withoptional aperture layers interposed). Alternatively, the instances offabrication might include stamping, routing, drilling, milling, oretching through holes and lateral cuts for fluidic channels in baselayers (e.g. FR4) followed by stacking and joining the layers withadhesive layers (e.g. prepreg FR4) as is known in the PCB art. Thelatter approach is preferable as it does not use metal layers to definefluidic channels thereby avoiding potential corrosion issues.

In the design of FIG. 6, the back of the chip/manifold 20 would beattached to the top of a Stablcor composite laminate. Optionally,depending on the board thickness, a molded plastic manifold layer (in alow CTE material such as a liquid crystal polymer or Shin EtsuKMC-6000HX epoxy molding compound) is attached to the bottom of theStablcor composite laminate with adhesive to provide some structuralrigidity. Later, all of the ports on the back of the Stablcor compositelaminate are combined into a single fluidic feature for each color ofthe ejection chip, tapering from a long slot to a single port on thebackside which can be easily connected by way of gasket approach. Wirebonds 22 down to the top surface of the laminate construct can made fromeither or both sides of the ejection chip (although it is only shown onits right side as oriented in the Figure).

With reference to FIG. 7, still another embodiment of a laminateconstruct in an ejection head is given. It is similar to that of FIG. 6,except for locating the manifold/chip 20 in a recessed pocket 80 of thelaminate construct and directly mounting the two with a die bondmaterial, as in FIG. 2. While not a requirement, mounting in thisfashion accomplishes two things. First, the best CTE match between thechip and construct is obtained. Second, the undersurface surface of thechip is mated directly to the highly thermally conductivity Stablcorlayer, thereby improving the thermal dissipation through thin bondlines. Even more, the thermal dissipation could be improved if the diebond material 61 included thermally conductive properties, such as thosefound with silica or boron nitride particles. A depth of the pocket, andthus the height of the top 81 of the manifold/chip 20 above a top 83 ofthe laminate construct, is made variable. In one instance, the pocketdepth is adjustable by varying a number of plies of prepreg used in theconstruct. The more the top surface of the manifold/chip 20 is madeflush with the top of the construct, the more advantage provided inmaintenance servicing for an easy wiping transition exists between thechip and construct. Such also eliminates the need for a separate cap,such as a plastic shroud piece as in certain prior art designs.

To create the pocket, routing or punching the upper or top layers ofprepreg of the construct are contemplated prior to laminating togetherits many layers. In initial experiments, the inventors have found thatdue to the heat and pressures involved in the lamination fabricationprocess, it may be necessary to maintain the space in the pocket byproviding a complementary feature in a press plate (not shown) thatprevents the underlying layers from becoming deformed into the pocketspace. Also, ceramics can be lapped to provide a nearly perfectly planarsurface, whereas PCB materials are less reliable. As such, PCB materialsmay require a thicker bond line to accommodate the substrate planarityvariation.

In other aspects of this embodiment, wire bonds 22 are shown runningbetween the chip and pads on the top layer of the construct. However,electrical pads can be formed in a bottom of the pocket to electricallyconnect the chip to the laminate construct. This enables a lower heightfor wire bond loops and a wider encapsulation height-process window.

With reference to FIG. 8, still another embodiment of a laminateconstruct 44 in an ejection head is given. In this design, a relativelythin construct is used and the tile 28 from earlier embodiments isretained. As seen, the tile mates to the backside of the construct 44 toprovide an even further lateral expansion or fan-out of fluidic channelsdownward from the manifold/chip 20. In addition, the plastic manifoldserves to provide structural support under the tile and tapering flowfeatures (not shown) for a gasket interconnection.

With reference to FIG. 9, multiple features of foregoing designs areprovided. Namely, the laminate construct 44 in an ejection headmaintains a recessed pocket 80 for the manifold/chip 20 and attachesabove a tile 28.

In alternate embodiments, it may be desired to eliminate the manifoldfrom the manifold/chip assembly 20. In such instances, the manifold iseliminated if the adhesive material, and its dispense process used toattach the assembly to the laminate construct, is capable of providingfluidic sealing across very narrow seal surfaces. Since a primaryfunction of the manifold is to provide increased sealing distances on aback or bottom side of the chip would be no longer required, themanifold is expendable. In such situations, the fluid flow features ofthe laminate construct would require adjusting to directly interfacewith those of the ejection chip.

Skilled artisans should readily appreciate the embodiments hereinpresent several options for fanning out fluid flow features downwardfrom an ejection chip and making electrical connections to a laminateconstruct. Layers of the construct and its construction techniques arealso revealed as are approaches to its attachment to still otherconventional structures in an ejection head. Relevant advantages havebeen described and other inherent advantages have been made readilyapparent.

The foregoing, therefore, is presented for purposes of illustrating thevarious aspects of the invention. It is not intended to be exhaustive orto limit the claims. Rather, it is chosen to provide the bestillustration of the principles of the invention and its practicalapplication to enable one of ordinary skill in the art to utilize theinvention, including its various modifications that naturally follow.All such modifications and variations are contemplated within the scopeof the invention as determined by the appended claims. Relativelyapparent modifications, naturally, include mixing and matching thefeatures of various embodiments with one another, if practical.

What is claimed:
 1. A micro-fluid ejection head for use in a micro-fluidejection device, comprising: an ejection chip to expel fluid toward aprint media during use; and a laminate construct, the laminate constructhaving a plurality of vertically configured wiring layers interspersedwith non-conductive layers, an upper layer of the wiring layers beingconductive to electrically connect to the ejection chip wherein each ofthe ejection chip and laminate construct have an ink feed slot in fluidcommunication with one another to convey said fluid through the laminateconstruct to the ejection chip, an undersurface of the ejection chip andthe laminate construct being connected.
 2. The ejection head of claim 1,further including a silicon tile in fluid connection with the ejectionhead and the laminate construct.
 3. The ejection head of claim 1,further including a plastic manifold supporting the laminate construct,the plastic manifold having a channel in fluid communication with theink feed slot of the laminate construct.
 4. A micro-fluid ejection headfor use in a micro-fluid ejection device, comprising: an ejection chipto expel fluid toward a print media during use; and a laminateconstruct, the laminate construct having a plurality of verticallyconfigured wiring layers interspersed with multiple non-conductivecarbon fiber layers, an upper layer of the wiring layers beingconductive to electrically connect to the ejection chip, an undersurfaceof the ejection chip and the laminate construct being connectedtogether.